1. Field of the Invention
The present invention relates to an access control management method, an access control management system and a terminal device with an access control management function which dynamically change a function to be used of a terminal device having a wired communication function or a radio communication function.
2. Description of the Related Art
As functions of portable terminal devices such as portable phones have been diversified, there have been an increasing demand for limiting the functions of portable terminal devices. It is desirable, for example, in a conference hall or a concert hall to stop a calling function or an incoming call ringing function of a portable telephone. In an art gallery or a book store, it is desirable to stop a photographing function of a portable terminal device with a camera. Under these circumstances, proposed is a system in which when a portable terminal device with a plurality of levels of use limit information stored in advance moves to a predetermined position, a base station designates use limit information related to the position (see e.g. Japanese Patent Laying-Open (Kokai) No. 2001-25070 (hereinafter referred to as Literature 1)). A control mechanism provided in the portable terminal device sets an internal state of the portable terminal device to be a state according to designated use limit information. Control mechanism of a portable terminal device in general includes a microprocessor which executes control processing according to an operating system (OS) and an application program.
Recited in Japanese Patent Laying-Open (Kokai) No. 2000-163379 (hereinafter referred to as Literature 2) is one example of a method of changing access control according to position information. More specifically, recited is a method of a terminal device of accessing only information according to its current position from a CD-ROM in which numbers of information is stored. “Access control” in the present specification denotes definition about which object is accessible by a subject in a terminal device. Here, subject represents an accessing body called a process, a program or an application. Object represents a resource managed in an OS such as a file or a directory (an arbitrary tool requested by a job or a task (equivalent to an object here) in a system using a computer, which includes a CPU, a storage device, an I/O device and a control program).
Furthermore, recited in Tresys Technology [searched on Jan. 23, 2004], Internet <URL: http://www.tresys.com/selinux/heckpolicy_prototype.html> (hereinafter referred to as Literature 3) is one example of a method of dynamically changing access control.
The system recited in Literature 1 is provided with a position detecting device which detects a current position of each portable terminal device existing in the system. The position detecting device detects the current position of each portable terminal device through a plurality of base stations and determines whether a function of each portable terminal device should be limited or not based on the detected current position. Then, when determining that the function of the portable terminal device should be limited, transmit function limiting information to the portable terminal device through the base station. The portable terminal device limits its own function based on use limit information designated by the function limiting information.
In such a system, disposing a position detecting device which detects every current position in the system increases costs for controlling functions of the portable terminal device as a whole of the system. In addition, while limiting a function of a portable terminal device is required by a demand of realizing a system inside a specific building or in a narrow region in proximity to the building, the system recited in Literature 1 finds it difficult to execute such strict position detection as satisfies the demand. Moreover, after a portable terminal device is brought into a building which allows no communication with a base station, function limiting information can not be transmitted to the portable terminal device.
On the other hand, with the access control management method recited in Literature 2, setting an access policy for each object in a terminal device is not possible. Neither possible is dynamically changing access control. The access control management method recited in Literature 3 requires one access policy covering access policies of all the geographical regions in which a terminal device is expected to locate to be prepared in advance, resulting in increasing a storage capacity in the terminal device. Moreover, it is impossible to cope with addition of an access policy related to a new geographical region.